A team from the U.S. Naval Research Laboratory (NRL) have broken their own record after flying their hydrogen fuel cell powered-Ion Tiger UAV for an astonishing 48 hours and 1 minute last month. The UAV, which used liquid hydrogen fuel in its new, NRL-developed, cryogenic fuel storage tank and delivery system, broke its previous record of 26 hours and 2 minutes which it set in 2009.
The NRL team used liquid hydrogen, which is three times denser than 5000-psi compressed hydrogen, allowing for more fuel to be carried on-board. This and the craft’s high quality, lightweight insulated flight dewar for the cryogenic fuel all helped to increase the UAV’s flight endurance.
“Liquid hydrogen coupled with fuel-cell technology has the potential to expand the utility of small unmanned systems by greatly increasing endurance while still affording all the benefits of electric propulsion,” said Dr. Karen Swider-Lyons, NRL principal investigator in a statement.
The team is now addressing the logistics of “in-theater supply” which would see in-situ manufacture of LH2 for use as fuel. All of this would be stored thanks to an electrolyzer-based system which would require only water for feedstock and electricity, possibly from solar or wind, to electrolyze, compress, and refrigerate the fuel.